Suncor Energy Inc., Canada’s largest energy company, is buying an additional 10 percent stake in the Fort Hills oil-sands mining project from Total SA for $234 million to lower its per-barrel cost and boost its return.

Suncor’s share in the C$15 billion project will increase to 50.8 percent in an agreement set to close later this year, the Calgary-based company said in a statement Monday. Total reduces its interest to 29.2 percent, furthering the French energy company’s goal to sell $10 billion in assets through 2017. A third partner, Teck Resources Ltd. holds 20 percent of the project.

The deal benefits Suncor, which has its U.S. headquarters in Denver, with a lower cost for the added Fort Hills interest as a market slump reduces investment in the oil sands, one of the most expensive places to extract crude. The deal follows Total’s decision last month to sell gas pipelines and a terminal in the U.K. for $906 million, and its move last year to shelve the C$11 billion Joslyn oil-sands mine because of high costs.

The purchase will mean another C$1 billion of capital investment in Fort Hills for Suncor, the company said. It may be viewed negatively by some investors because it diverts cash away from share repurchases and increases the company’s exposure to a project that’s seen as a marginal supply source, Randy Ollenberger, an analyst at BMO Capital Markets in Calgary, wrote in a research note.

“The price of oil has brought into question the economic viability of Fort Hills,” said Michael Kay, an analyst at Bloomberg Intelligence. “The upfront costs are very high.”

The mine, located north of Fort McMurray, Alberta, is expected to start operating in 2017 and will ramp up to 180,000 barrels a day.

Suncor climbed 1.7 percent to C$34.65 at 11:58 a.m. in Toronto, while Total shares rose 0.1 percent to 40.82 euros at the close of trading in Paris.

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